Triple valve.



PATENTED JUNE 30, 1908.

No. 892,101.V

E. C. WASHBURN.

TRIPLE VALVE.

APPLIOATION FILED SEPT. 1e, 1907.

2 SHEETS--SHEBT 1.

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PATENTED JUNE 30, 1908. E. G. WASHBURN.

TRIPLE VALVE.

APPLICATION FILED BEPT.16, 1907.

2 SHEETS-SHEET 2.

UNITED STATES PATENT OFFICE.

EDWIN C. WASHBURN, OF MINNEAPOLIS, MINNESOTA.

TRIPLE VALVE.

To all 'whom it may concern:

Be it known that I, EDWIN C. WAsHBURN, a citizen of the United States, residing at Minneapolis, in the county of Hennepin and State of Minnesota, have invented certain new and useful Improvements in Triple Valves; and I do hereby declare the following to be a full, clear and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

My invention relates to air brake apparatus, and has for its especial object to provide a highly efficient triple valve of extremely simple construction.

To the above ends, the invention consists of the novel devices and combinations of devices hereinafter described and defined in the claims.

My improved triple valve comprises a differential cylinder, a differential piston working therein, and a spring or means for producing an approximately constant tension of yielding force in opposition to the variable air pressure on the relatively large area of said piston, which cylinder and piston are provided with coperating ports. When this triple valve is applied in an air brake system employing a train pipe, an auxiliary reservoir and a brake motor, the relatively large and small ends or pressure surfaces of the piston are continuously subject to train pipe ressure, so that air pressure acting on said ifferential piston always tends to maintain said valve in its normal position, to-wit, in a position to maintain communication between the train pipe and the auxiliary reservoir, and to cut ofi the brake cylinder both from the train pipe and auxiliary reservoir. The spring exerts a force on the piston which augments the air pressure on the small end of said valve, and tends to move said valve from its normal position into its other extreme position, to-wit, into a position to cut the train pipe off from the auxiliary reservoir and brake cylinder and to open up communication between the auxiliary reservoir and said brake cylinder. The tension of the said spring should be such in respect to the air pressure on the two ends or opposing pressure surfaces of the piston that under normal train pipe pressure, said piston will be held in its normal position above indicated, but when the train pipe pressure is reduced, say five pounds below normal, said piston will be moved to its other ex- Specication of Letters Patent.

Application filed September 16, 1907.

Patented .Tune 30, 1908.

Serial No. 393,008.

treme position, also above indicated. A specific illustration of these relative proportions of the opposing pressure surfaces of the piston and of the tension of the spring will be given in connection with the description of the improved triple valve, as illustrated in the drawings.

In the drawings, like characters indicate like parts throughout the several views.

Referring to these drawings, Figure 1 is a horizontal section taken longitudinally and centrally through a triple valve designed in accordance with my invention, and illustrating, diagrammatically, a train pipe, auxiliary reservoir and brake cylinder connected to the cylinder of said triple valve and Figs. 2 and 3 are horizontal sections, with parts broken away, illustrating different positions of the piston of the said triple valve.

The differential cylinder l has a relatively long section 1a of relatively small diameter, and a relatively short section 1b of relatively large diameter. As shown, the outer end of the cylinder section 1a is closed by a threaded head 2, and the outer end of the cylinder section 1b is closed by a threaded head 3. The cylinder section 1u is provided with ports 4, 4, 5 and 6. The ports 4 and 4a are connected by a suitable conduit 7 to the train pipe 8; the port 5 is connected by a conduit 9 to the auxiliary reservoir 10, and the port 6 is connected by a suitable conduit 11 to the brake cylinder 12.

The differential piston 13 which works within the differential cylinder has its relatively small end 13 arranged to work and exposed within the cylinder section 1a, and has its relatively large end 13b arranged to work and exposed within the cylinder section 1b. An air conduit 14, as shown, extends axially through the piston 13, and an annular air chamber 15 is formed within said piston immediately surrounding the said conduit 14. Furthermore, said piston is provided with ports 16, 17, 18 and 19. In the normal position of the piston 13 shown in Fig. 1, the piston port 16 registers with the cylinder port 4; the piston port 19 registers with the cylinder port 5; and the piston ports 17 and 1S and the cylinder port 6 are closed. As a simple means for preventing rotation of the piston 13 a set screw 20 is secured through the cylinder and engaged with a longitudinally extended guide groove 21 in said piston. The spring, which is preferablyY in the form of a coiled spring 22, is

placed within the cylinder section '1'6L and is compressed between the cylinder head 2 and the small end of the piston 13. By adjustments of the said head 2 the tension of the said spring may be varied.

The exact relation of the several coperating ports of the cylinder and of the piston above described will be more clearly given in the following description of the operation. For the purposes of illustration we will assume that normal train'pipe pressure is 70 pounds; that under pounds pressure per square inch the total air pressure on the large end of the pistonk is 179 pounds, while the total air pressure on the small end of said piston is 142 pounds; and that the pressure of the spring 22 on said piston is 36 pounds. l/Vith these assumed conditions, when a train pipe pressure of 70 pounds is maintained, the piston will be held in its normal position by an air pressure of 17 9 pounds on its large end, acting against an aggregate air pressure and spring pressure of 178 pounds.

When both the train pipe pressure is reduced 5 pounds, or to a pressure of 65 pounds per square inch, the total air pressure on the large end of the piston will be approximately 166 pounds, while the total air pressure on the small end of said piston will be approximately 132 pounds. This air pressure of 132 pounds, augmented by the 36 pound pressure of the spring 22, will give a total pressure of 168 pounds, tending to move the valver from its normal position, as against the total air pressure of 166 pounds, tending to maintain said piston in its normal position. Hence, of' course, under this reduced train pipe pressure, the piston will be moved iirst to the position shown in Fig. 2 and then to the position shown in Fig. 3. The speed at which this movement of the piston will take place will depend very largely on the size of the cooperating ports in the cylinder and the piston.

. When the piston reaches its intermediate position shown in Fig. 2, it closes the port 5 and cuts oil the auxiliary reservoir, but opens up for a short period of time, communication between the train pipe and the brake cylinder, by way of the ports 4, 16, 18 and 6, and this gives aninitial charge of air from the train pipe into the brake cylinder, so that equalization of pressure between the auxiliary reservoir and brake cylinder, under further movement of the said piston, will be higher than if this independent initial charge were not given.

When the piston reaches its extreme position indicated in Fig. 3, the ports 4 and 16 are closed, thereby cutting the train pipe out of communication both with the auxiliary reservoir and brake cylinder, but communication is then opened up between the auxiliary reservoir and brake cylinder by way of the ports 5, 17, 18 and 6. When the train pipe pressure is again restored to the assumed normal pressure of 7 0 pounds, or to a higher pressure, the total air pressure on the large end of the piston will, of course, again exceed the combined pressure of the air and of the spring on the small end of the piston, and the said piston will be again restored to its normal position shown in Fig. 1.

The above described triple valve has very few parts and consequently is of very small cost and is not likely to get out of order. Furthermore, it is eliicient for the purposes had in view` i The terms cylinder and piston are herein used in a broad sense to indicate the valve casing and a plunger -like valve mounted to reciprocate or vibrate therein, regardless of the exact form of the said parts.

The spring herein employed to augment the action of the air pressure on the small end of the piston is, in a broad sense, a yielding pressure device of' approximately constant tension. Its tension may vary slightly under expansion and contraction, but must not follow variations in the train pipe pressure. Whatever form this so-called constant tension device may take, it must be such that under normal train pipe pressure its force, added to the air pressure on the small end of the piston, will not equal the total air pressure on the large end of the piston, but must be such, nevertheless, that under a predetermined reduction of train pipe pressure its force, added to the air pressure on the small end of the piston, will exceed the total air pressure on the large end of the piston.

What I claim is:

1. A triple valve comprising a differential cylinder, a differential piston working therein, and a yielding constant tension device exerting a force tending to move said piston in opposition to the air pressure on the relatively large end or pressure area of said piston, said cylinder and piston having coperating ports, substantially as described.

2. A triple valve comprising a diferential cylinder, a differential piston working therein, and a spring within said cylinder exerting a force on said piston tending to move the same in opposition to the air pressure on the large end or pressure area of said piston, said cylinder and piston having coperating ports, substantially as described.

3. In a triple valve, the combination with a differential cylinder having train pipe auX- iliary reservoir and brake cylinder connections, of a differential piston within said cylinder, having ports operative in one position of said piston to open up communication between the train pipe and auxiliary reservoir connections, and operative in another position to cut off communication between said train pipe and auxiliary reservoir connections and open up communicationbetween said auxiliary reservoir connection and brake cylinder connection, and a yielding constant tension device exerting force on said piston tending to move the same from its first noted to its second noted position, substantially as 'described.

4. In a triple valve mechanism, a train pipe, auxiliary reservoir and brake cylinder, in combination with a triple valve comprising a differential cylinder having ports connected to said train pipe, auxiliary reservoir and brake cylinder, a differential piston working within said differential cylinder and subject at both ends to train pipe pressure, and a spring exerting force on said piston tending to move the same against air pressure on the large end thereof, said piston having ports arranged for cooperation with the ports of said differential cylinder to open up communication between the train pipe and auxiliary reservoir in one position of said piston, and in another position of said piston to cut off communication between said train pipe and auxiliary reservoir and to open up communication between said auxiliary reservoir and brake cylinder, substantially as described.

5. In a triple valve, the combination with a differential cylinder having train pipe, auxiliary reservoir and brake cylinder connections, of a differential piston within said cylinder subj ect to train pipe pressure at both ends, and a spring exerting force on said piston tending to move the same against the air pressure on the large end thereof, the said cylinder and piston having cooperating ports so arranged that in the normal position of said piston said train ipe and auxiliary reservoir connections wil be in communication, in an intermediate position of said iston said auxiliary reservoir connection wil be closed and said train pipe connection will be in communication with said brake cylinder connection, and in the other extreme position of said piston said train pipe connection will be closed and said auxiliary reservoir and brake cylinder connections will be in communication, substantially as described.

6. In a triple valve, a differential cylinder and differential piston having coperating ports, the relatively large and small areas of said piston being subject to the opposing force of variable air pressure, and the said piston being also ,subject to an approximately constant pressure that acts in opposition to the air pressure on the relatively large area thereof.

In testimony whereof I affix my signature in presence of two witnesses.

EDWIN C. WASHBURN.

Witnesses:

MALIE HOEL, H. D. KILGORE 

